Graft copolymer dispersions prepared from vinyl monomers and polyether polyols, and their use in the preparation of polyurethane polymers are well known as described in U.S. Pat. Nos. 3,383,351 to Stamberger and 3,652,639 to Pizzini et al. In the earlier patent, the polyols employed are essentially free from ethylenic unsaturation. The polyols employed by Pizzini et al contained at least about one mole of unsaturation per mole of polyol. In accordance with this invention a variety of polyols can be used in conjunction with para-methylstyrene.